Remove unused parameter from, and add safeguard in, get_room_data (#8174)

Small cleanup PR.

* Removed the unused `is_guest` argument
* Added a safeguard to a (currently) impossible code path, fixing static checking at the same time.

1 files changed, 1 insertions, 1 deletions

diff --git a/tests/rest/client/test_retention.py b/tests/rest/client/test_retention.py

index d4e7fa1293..7d3773ff78 100644
--- a/tests/rest/client/test_retention.py
+++ b/tests/rest/client/test_retention.py
@@ -178,7 +178,7 @@ class RetentionTestCase(unittest.HomeserverTestCase):
         message_handler = self.hs.get_message_handler()
         create_event = self.get_success(
             message_handler.get_room_data(
-                self.user_id, room_id, EventTypes.Create, state_key="", is_guest=False
+                self.user_id, room_id, EventTypes.Create, state_key=""
             )
         )